Fibrous carbon materials, and in particular fibrous carbon nanostructures such as carbon nanotubes (hereinafter, also referred to as “CNTs”), have been attracting interest in recent years as materials having excellent electrical conductivity, thermal conductivity, and mechanical properties.
However, fibrous carbon nanostructures such as CNTs are fine structures having nanometer-size diameters, which makes handling and processing of individual nanostructures difficult. Therefore, it has been proposed that, for example, a solution containing dispersed CNTs may be prepared and applied onto a substrate or the like in order to cause a plurality of CNTs to assemble into the form of a film to form a carbon nanotube film (hereinafter, also referred to as a “CNT film”) that can then be used as a conductive film or the like. A CNT film such as described may also be referred to as “buckypaper”. In one known example of an application liquid in which CNTs are dispersed, the application liquid contains high-purity CNTs that are dispersed in a solvent (refer to PTL 1).